This invention relates to a refrigerated display cabinet having air defrost capacity, and more particularly to such a cabinet having areodynamic isolation of the refrigeration coil from the product storage and display space during air defrost of the coil.
The high cost of energy in recent years has prompted efforts to develop commercial refrigerated display cases not requiring added energy, e.g. electrical or heated gas, for periodic defrosting of the coil. These efforts, largely applied to display cases of the open front, multiple curtain type, have resulted in cabinets which are defrosted by flow of ambient air through the cabinet duct system that extends around the product zone, generally separated therefrom.
When a "reach-in" type of display cabinet, however, i.e. one having physical access doors, usually of glass, on the front, the refrigerated air is circulated from the coil directly through the product storage and display space and back to the coil during normal operation. However, during defrost, it is not desirable to circulate warm defrosting air through this storage product because of warming and/or melting of the product and frost formation on the product surfaces. Therefore, it would be desirable to air defrost such display cases without significant flow of warm defrost air through the product space. One conceivable technique would be to keep the warmer air out of the product space by dampers or doors in the ducts. However, such devices have a tendency to freeze shut or open to cause maintenance problems in portions of the case not readily accessible.